Removable, portable circuit components, such as portable memory cartridges, have been utilized in computer and video game terminals for a number of years. Such memory cartridges have a connector on one end which plugs into a connector mounted on the terminal. To protect the memory cartridge, it is imperative that the supply of electrical power to the cartridge be turned off prior to either insertion or removal of the cartridge from the connector.
A variety of approaches have been taken to protecting removable circuit components from damage due to electrical transients that are produced if the component is removed or inserted while power is being applied to the connector pins. For example, in some video games and personal computers that utilize ROM program cartridges, an access cover is provided over the connector and cartridge and a power cut-off switch is operatively associated with the cover so that the electrical power to the cartridge connector is cut off when the cover is opened regardless of whether the main power switch of the unit is on or off. The use of a separate cover with power switch interlock is not an attractive design arrangement for the small terminal and portable computer environment.
In some portable memory cartridge applications, the system relies solely on different pin lengths in the connectors to sequence the connection and disconnection of power supply voltages to the cartridge as it is being removed or inserted. In other words, the lengths of the pins is arranged so that pins carrying power are connected last and disconnected first.
In some systems, the portable memory cartridge itself is inserted directly into the unit using a guide arrangement to assure alignment of the connector pins as the device is inserted. In this arrangement, one end of the portable memory cartridge must extend outside the housing walls to provide a place to grasp the component for disconnecting it from the system. This arrangement leaves the portable memory cartridge subject to possibilities of being struck by some object which might damage it or the connector arrangement. In other systems, the portable memory cartridge is carried in a tray to protect the system, but there is no positive interlock on the tray which turns off the power to the portable memory cartridge prior to beginning to remove the cartridge and tray from the system.
It is also known in the prior art to provide for a special arrangement on the tray carrying the portable memory cartridge cooperating with extra pins on the connector to switch power to the portable memory cartridge on and off as the tray is inserted and removed.